The prior art has disclosed various apparatus for transporting magnetic tape past a magnetic transducer for the writing and reading of information on the tape. As a general rule, the type of transport employed is generally related to the type of information that is to be recorded on the tape to be transported. Where digital data is stored on the tape and the information is recorded from or read out to a data processing system, the characteristics of the tape transport are considerably different from tape transports employed, for example, in audio types of recorders. In tape transports for use with data processing systems, the tape speed, acceleration and deceleration, characteristics are considerably more stringent.
A number of reel-to-reel capstanless tape transports have been disclosed in the art where a separate drive motor is associated with each reel and a control system is provided for the motors which results in the take-up reel effectively pulling the tape through the tape path past the magnetic transducer or the supply reel, which is generally removable, pulling the tape back from the take-up reel through the tape path in the reverse direction. As a result, tape that is wound on either reel is usually wound under tension resulting in each layer imposing a a radial compressive force on previously wound layers.
The radial forces exerted on the inner layers results in a problem whenever a discontinuity is formed in the cylindrical surface of the hub or a discontinuity is formed at the point where the end of the tape is attached to the reel hub. The problem results in a "tenting" of the tape as it passes the read-write gap of the magnetic transducer on the narrow segment of the tape which overlapped the initial discontinuity. The degree of "tenting" and the seriousness of the problem is directly related to the size of the discontinuity, the radial forces resulting from wrapping the tape under tension, the length of time the layers are exposed to the discontinuity, and the material from which the media is manufactured.
It has been found in accordance with the present invention that by forming a portion of the cylindrical section of the hub to function as a cantilever type beam in the area where the end of the tape first engages the cylindrical hub of the reel, subsequent layers of the tape have less tendency to "tent" since the radial pressure is reduced at the discontinuity by the bending action of the cantilever beam. Further reduction in "tenting" can be achieved if the outer portion of the hub is made more compressible relative to the inner portion of the hub which is coupled to the drive motors. The outer portion may be made more compressible by providing a series of openings in the outer solid portion of the hub or by a suitable choice of materials different than the materials employed for the inner portion of the hub.
By providing a take-up reel where the portion of the hub which attaches to the drive motor is solid, rigid, and uncompressible and the outer portion of the hub is compressible in a radial direction, the radial forces imposed on each layer of tape is substantially decreased, and the possibility of a discontinuity causing a "tenting" of the tape as it passes the magnetic transducer is considerably reduced.
It is, therefore, an object of the present invention to provide an improved take-up reel for use in a web transport operation.
A further object of the present invention is to provide an improved reel for magnetic tape to be employed in a tape transport wherein the tape may be wound on the reel under tension.
A further object of the present invention is to provide a take-up reel in which the hub of the reel has an outer compressible portion extending radially inward to a relatively solid, noncompressible inner portion which is adapted to be connected to the shaft of the driving motor.
A still further object of the present invention is to provide an improved reel for magnetic tape of the type in which the cylindrical surface of the reel hub on which the first layer of tape is wrapped is not continuous, resulting in a pair of spaced discontinuities defined by the adjacent edges of the cylindrical surface where the outer cylindrical portion of the hub is radially compressible and the inner cylindrical portion is relatively noncompressible.